1. Field of the Invention
The invention relates to a pulling tool of the type used on the end of a shaft to remove a mechanical part force-fitted to the shaft. The tool comprises a body to which are hinged legs that each have a free end designed to bear on a rear face of the mechanical part to be removed, and a central threaded rod capable of a screw action relative to the body and to the legs, its proximal end has rotational driving means and its distal end being designed to bear on a free front end of the shaft.
2. Description of Related Art
Such tools are often used for withdrawing pulleys or discs from their shaft, or rolling bearings mounted around a shaft or inside a hollow shaft. After a prolonged period of use, the connection between these mechanical parts and their shaft can become seized up so that a very considerable extraction force is required to separate these mechanical parts from their shaft.
In addition, friction between the threaded rod of the pulling tool and the body of the tool in which the rod is mounted tends to cause the body and the legs to be carried round with the threaded rod when the rod is rotated by the user. This causes a loss of relative translational movement between the threaded rod and the body, and users naturally tend to solve this by inserting a restraining tool such as a bar between one leg and the threaded rod in order to stop the legs and the body from rotating and enable the threaded rod to move translationally with respect to the body.
In view of the large forces involved, the pressure of a bar used in this way against the threaded rod causes very noticeable damage to the threads of the rod, to the point that the tool can be made unusable.
It is a principal object of the invention to overcome this problem and to provide a very inexpensive device that will save the threaded rod of a pulling tool from becoming damaged by a member for inhibiting rotation of the legs.
The device according to the invention includes a sleeve for a pulling tool of the abovementioned type. The sleeve is characterized in that it can be mounted on the threaded rod and can form a bearing member for a member which inhibits rotation of the legs during screwing of the threaded rod.
Other characteristics are as follows:
the sleeve consists of a nut able to be screwed onto the threaded rod;
the sleeve consists of a nut of the speed-nut type;
the sleeve consists of a part that slides along the threaded rod, with a locking member engaging with the threads of the rod, the locking member being operated by a user;
the outer surface of the sleeve comprises a groove;
the sleeve has the general external form of a diabolo;
the outer surface of the sleeve is essentially cylindrical and has at least one flat;
the outer surface of the sleeve is essentially polyhedral;
the length of the sleeve is greater than its maximum diameter;
the sleeve consists of an essentially cylindrical sleeve with a blind hole in its periphery designed to take the rotation-inhibiting member; and
the sleeve consists of an essentially cylindrical sleeve, on the outer surface of which is a projecting lug containing a drilled hole designed to take the rotation-inhibiting member.
The invention also relates to a pulling tool of the abovementioned type comprising a sleeve as described above.
The invention relates furthermore to a method of removing a mechanical part force-fitted or stuck to a shaft, involving use of a tool of the abovementioned type, characterized in that the method comprises the following steps:
a sleeve as defined above is fitted onto the threaded rod of the tool;
the tool is placed at the end of the shaft so that the legs grip the mechanical part to be removed;
the threaded rod is screwed down onto the shaft until the tool is held firmly on the mechanical part to be removed;
the sleeve is positioned axially on the threaded rod;
a member for inhibiting rotation of the legs is held against at least one of the legs and against the protective bearing sleeve; and
the threaded rod is rotated while the tool is kept stationary by the rotation-inhibiting member, in such a way as to remove the mechanical part from the shaft.